Magnetic proximity interface control

ABSTRACT

Disclosed is a system and method employing a magnetic proximity switch to enable the transfer of power between a power supply unit and a docking unit or to transfer data between a docking unit and a peripheral module such as a disk drive or controller module. Power may be transferred through the switch, or a signal from the switch may be employed to enable a control circuit. The control circuit may control a plurality of voltages or currents and may ramp voltages or currents to limit surge current when a module is installed or removed. The control unit may also be employed to place data and control signals in a high impedance state when a module is not docked, limiting electromagnetic radiation.

BACKGROUND OF THE INVENTION

[0001] a. Field of the Invention

[0002] The present invention pertains to computer interface control andmore specifically to a system and method employing magnetic proximitydetection to enable or disable an interface.

[0003] b. Description of the Background

[0004] Storage systems typically comprise an array of disk drives, diskdrive controllers, power supplies and interface cabling. Systems areoften redundant in that there are duplicate controllers, duplicate powersupplies and duplicate buses interconnecting controllers, drive arrays,and power supplies. Further, systems are often constructed to be readilymaintainable and upgradeable. Various components of the system may bereplaced while the system continues to operate. For example, if a powersupply failure occurs, the failed power supply may be replaced while thesystem continues to operate using another functioning power supply orpower supplies. Similarly, if a controller fails, the system maycontinue to operate using another functioning controller while thefailed unit is replaced. These capabilities are often realized through amodular architecture. Typically, various modules comprising disk drives,controllers, power supplies and such, are disposed in a single cabinetor housing. The cabinet provides connections between the variousmodules, including detection of the presence of modules. The cabinetsand associated modules must meet federal requirements for safety andelectromagnetic radiation. Each opening in the cabinet, such as isrequired for connectors, presents a potential safety hazard if highvoltages are present, and also presents an opportunity forelectromagnetic radiation to escape the cabinet. Further, the insertionand removal of components may result in spikes or distortion to powersupply voltages and data and control signals. Installation of a modulemay result in a momentary current surge as the module powers up. Somesystems employ a ‘bay’ architecture into which modules may be inserted,wherein power signals are typically at the back of the bay and are lesslikely to be touched by personnel. Safety switches may be employed tolimit exposure to harmful voltages, but such switches present a point offailure and may degrade after repeated insertions due to switching highcurrent. Further, these systems do not address potential problems ofpower spikes and current surges that may affect system operation and mayreduce module operating life. Therefore a new system and method forcontrolling interfaces in component architectures is needed.

SUMMARY OF THE INVENTION

[0005] The present invention overcomes the disadvantages and limitationsof the prior art by providing a magnetic proximity controlled interfacethat enables signals in response to the presence of a magnetic field.The present invention may be employed to control interfaces for bothpower and data/control signals. By not driving an interface connectorwhen a module is not present, electromagnetic radiation may be reduced.The present invention may also reduce the number of pins required inconnectors by employing the magnetic proximity controlled interface tosignal that a module is present rather than employing a signal pin in aconnector.

[0006] The present invention therefore may comprise a method forremovably connecting a power supply module to a docking unit in anelectrical system comprising: producing a signal from a switch disposedin the docking unit when the power supply module is docked to thedocking unit wherein the switch is responsive to a magnetic fieldproduced by a magnet affixed to the power supply module; inputting thesignal to a power control circuit; transferring a first voltage from thepower control circuit to the power supply module when the signal isactive; inhibiting transfer of the first voltage from the power controlcircuit to the power supply module when the signal is not active; andtransferring a second voltage from the power supply module to thedocking unit.

[0007] The invention may further comprise a method for removablyconnecting a storage system module to a docking unit in an electricalsystem comprising: producing a signal from a switch disposed in thedocking unit when the storage system module is docked to the dockingunit wherein the switch is responsive to a magnetic field produced by amagnet affixed to the storage system module; inputting the signal to apower control circuit; transferring a first voltage from the powercontrol circuit to the storage system module when the signal is active;inhibiting transfer of the first voltage from the power control circuitto the storage system module when the signal is not active; enablingdata signals connecting the storage system module and the docking unitwhen the signal is active; and placing the data signals in a highimpedance state when the signal is not active.

[0008] The present invention may additionally comprise an electricalconnection system comprising: a cabinet including at least one dockingunit; a module that may be docked to the docking unit; a non-magneticarea in a portion of at least one surface of the docking unit; a magnetaffixed to the module; a switch disposed in the non-magnetic area of thedocking unit; and a circuit that receives a switch signal from theswitch and that transfers a voltage from the docking unit to the modulethrough a connector when the switch signal is active and that inhibitstransfer of the voltage from the docking unit to the module when theswitch signal is not active.

[0009] Advantageously, the present invention provides a system andmethod of connecting components that limits exposure to unsafe voltagelevels, reduces potential electromagnetic emissions, and may providelower cost through reduced complexity of connectors and signal lines.

DESCRIPTION OF THE FIGURES

[0010] In the figures,

[0011]FIG. 1 is a depiction of a storage system.

[0012]FIG. 2 depicts a magnetic proximity controlled power interface.

[0013]FIG. 3 depicts a magnetic proximity controller power interfaceemploying two switches.

[0014]FIG. 4 depicts a magnetic proximity controlled interface for adisk drive or controller.

[0015]FIG. 5 depicts a magnetic proximity controlled interface for adisk drive, controller, or other module employing two switches.

[0016]FIG. 6 depicts magnet placement.

DETAILED DESCRIPTION OF THE INVENTION

[0017]FIG. 1 is a depiction of a storage system. Storage system 100comprises controllers 102, 104, disk drive arrays 106, 108, and powersupplies 110, 112. Power bus 122 provides power to the controllers anddrive arrays. Controller 102 is connected to disk drive array 106through a first data/control bus 116 and to disk drive array 108 througha second data/control bus 118. Controller 102 communicates data to anexternal system through external interface 114. This interface maycomprise an Ethernet bus, SCSI (Small Computer Systems Interface) bus,fibre channel connection, or other type of interface, either serial orparallel. Similarly, controller 104 is connected to disk drive array 106through first data/control bus 116 and to disk drive array 108 throughsecond data/control bus 118. Controller 102 also communicates data to anexternal system through external interface 114. In some implementations,controller 102 and controller 104 may employ separate interfaces (notdepicted) to communicate data to an external system. Controllers 102,104 each employ one or more connectors to receive power from power bus122 and to interface to first data/control bus 116, second data/controlbus 118, and external interface 114. Disk drive arrays 106, 108 eachemploy one or more connectors to receive power from power bus 122 and tointerface to first data/control bus 116 or second data/control bus 118.Although not depicted, in some implementations, disk drive arrays mayinterface to both first data/control bus 116 and second data/control bus118. Power supplies 110 and 112 receive external power from externalpower bus 120. External power bus 120 may supply line voltages such as120 volts AC or 240 volts AC as is common in North America, or maysupply other voltages in different countries. Power supplies 110, 112convert the line voltage of external power bus 120 to a voltage (orvoltages) used by controllers 102, 104 and disk drive arrays 106, 108and outputs the voltage (or voltages) on power bus 122. Some systems mayemploy redundant power buses (not depicted) such that a plurality ofpower buses are connected to each system component. System 100 may alsoinclude one or more ESMs (Environmental Service Monitor), not depicted,that provide monitoring of the system. Monitoring may includetemperature, power supply voltages, cooling fan operating informationand the like. The ESM or ESMs are typically interfaced to thecontrollers such that operating conditions may be conveyed to anexternal system. The system of FIG. 1 is illustrative of the componentscomprising a storage system. System architectures may vary with the sizeand capabilities of the system. Large system modules may comprise ‘tray’architectures wherein a plurality of drives and one or more powersupplies may be contained in a removable tray. The tray may furthercontain one or more ESMs and may contain one or more storagecontrollers. Other architectures may employ modules comprising one ormore storage controllers and one or more power supplies. The presentinvention, as shall be later described in detail, is applicable to anyarchitecture employing removable modules containing one or more systemcomponents. Power supplies may be internal to modules, external tomodules as part of a cabinet, or may comprise a removable module.

[0018] Storage systems are typically modular in architecture such thatfailed components may be readily replaced or additional components addedto repair or upgrade the system. The storage system may comprise acabinet with slots or bays into which controller, disk drive and powersupply modules may be installed. Connectors on each module provide aninterface to power and/or data/control signals. Systems must comply withfederal safety and electromagnetic emissions standards. UnderwritersLaboratories (UL), headquartered in Northbrook Ill., typically certifiessystems. UL imposes limitations on a user's exposure to unsafe voltagelevels. Some architectures employ safety switches to limit exposure tounsafe voltages. However these switches typically switch high currents,resulting in potential contact damage and failure over time. Further, ahole may be employed in the module casing to allow activation of theswitch, providing a potential leak for electromagnetic radiation. Thepresent invention overcomes the aforementioned limitations by conveyinga magnetic field through a non-ferrous surface, such as aluminum, forexample, that activates a switch. The switch then may be used to controla power switching device.

[0019]FIG. 2 illustrates a magnetic proximity controlled powerinterface. Docking unit 200 comprises connector 202, power switchingdevice 204, switch 206, connector 208 and bulkhead 210. An opening inbulkhead 210 allows access to connector 208. Switch 208 is disposed onor near the surface of bulkhead 210. Power supply unit 212 comprisesmagnet 214, connector 216 and bulkhead 218. An opening in bulkhead 218allows access to connector 216. Magnet 214 is affixed to bulkhead 218.The term affixed is defined to mean that the magnet 214 may be on ornear an inner surface of bulkhead 218, in an opening in bulkhead 218, oron or near an exterior surface of bulkhead 218, as shall be laterillustrated in FIG. 6. In operation, power supply unit 212 is positionedsuch that connector 216 is opposite but separated from connector 208 andmagnet 206 is opposite but separated from switch 206. Power supply unit212 is moved toward docking unit 200 and conductors of connector 216make contact with conductors of connector 208 prior to activation ofswitch 206 by magnet 214. The power supply unit is then moved towarddocking unit 200 until connectors 208 and 216 are mated and switch 206is activated by magnet 214. Once switch 206 is activated, an enablesignal is transferred to power switching device 204. Switch 206 maycomprise a reed switch from Hamlin, a subsidiary of Breed Technologiesheadquartered in Lakeland Fla. A reed switch has two ferromagnetic reedsthat are hermetically sealed into a glass capsule that may contain inertgases or a vacuum. The reeds overlap and are separated by a small gap inthe contact area. Contact surfaces may be precious metal, semipreciousmetal or mercury wetted. In the presence of a magnetic field the reedsclose and open again when the magnetic field is removed. Power switchingdevice 204 may comprise a relay, a solid-state relay, silicon controlledrectifiers or other power switching devices. Some solid-state relaysaccept line voltage as a control input, such as those from Potter &Brumfield (a subsidiary of Tyco International Ltd., headquartered inPembroke, Bermuda.), simplifying the number of components required andreducing the likelihood of failure. The enable signal from switch 206causes power switching device 204 to transfer power from connector 202to connector 208, providing line voltage to power supply unit 212. Powersupply unit 212 typically supplies other voltages to unit 200 that maybe conveyed through connector 216 or another connector. Power supplyunit 212 may be constructed such that upon receiving power fromconnector 216, output voltages are ramped to their fall value to reducespiking. Further, Power supply unit 212 may receive a current signalfrom another power supply, as may be conveyed through connector 216,which may be employed to balance the load between the supplies.Advantageously, the magnetically controlled interface of FIG. 2 allowsdocking unit power connectors to be at or near to ground potential whena power supply unit is not installed, reducing shock hazards andpossible electromagnetic radiation when a module is not installed. Assuch the configuration and maintenance of modular systems may beperformed in greater safety and convenience. Further, the presentinvention may be employed to ramp power to an installed module, reducingpossible spikes or surges in power signals and reducing possible stressto circuitry. This may result in greater system reliability andoperating longevity.

[0020]FIG. 3 depicts a magnetic proximity controller power interfaceemploying two switches. While similar to FIG. 2, the interface of FIG. 3adds magnet 308 to docking unit 300 and also adds switch 318 and powercontrol 320 to power supply unit 312. Switch 318 is closed when thepower supply unit 312 is docked to docking unit 300. When power supplyunit 312 is removed, there exists a position where connector 316 is incontact with connector 310 but switch 318 is open. When this occurs,power control 320 may be employed to ramp voltages down, reducingspiking and placing a sudden increase in load on other power supplies inthe system.

[0021] The present invention may also be employed with disk andcontroller modules wherein the power to the modules may be ramped inorder to limit surge current. FIG. 4 depicts a magnetic proximitycontrolled interface for a disk drive, controller, or other module.Docking unit 400 comprises switch 402, switch supply line 404, switchoutput line 406, control unit 408, power supply line 410 and connector412. Module 420 comprises magnet 414, connector 416 and module powerline 418. When module 420 is docked to docking unit 400, magnet 414activates switch 402, providing transfer of switch supply line 404voltage to switch output line 406. The voltage supplied by switch supplyline 404 is a sufficient to activate or provide an indication to controlunit 408 and may comprise a wide range of voltages. Switch output line406 serves as an input signal to control unit 408. Switch output line406 may also be used to provide an indication that module 420 is docked.Control unit 408 transfers power from power supply line 410 to connector412. Such transfer may include ramping voltages when a voltage isdetected on switch output line 406. In such a manner, spikes and surgecurrent may be reduced. Control unit 408 may also be employed to enableand disable driving of data and control signals to module 420. As such,the present invention may be employed to control interfaces for bothpower and data and control signals. By not driving data and controlsignals when a module is not present, electromagnetic radiation may bereduced. This may also result in higher system reliability since anunused connector, even if contaminated with dirt, dust, and foreignobjects, will not affect operation of the system.

[0022]FIG. 5 depicts a magnetic proximity controlled interface for adisk drive, controller, or other module employing two switches. As inFIG. 4, the system of FIG. 5 employs magnet 516 disposed in module 526to activate switch 506 disposed in docking unit 500. Switch output line506 is employed to signal control unit 508 and may be employed toprovide an indication that module 526 is docked. As in FIG. 4, controlunit 508 is responsive to switch output signal 506 and may connect powersupply line 510 to connector 512 and may ramp voltages in response to atransition of switch output line 506. Further, control unit 508 mayenable data and control lines in response to switch output line 506.Docking unit 500 also includes magnet 514 that communicates with switch522 disposed in module 526. Switch 522 is activated as module 526 isdocked with docking unit 500 and is deactivated when module 526 isundocked from docking unit 500. When module 526 is being undocked,switch 522 may be deactivated prior to the breaking of a connectionbetween connector 512 and connector 518. Switch output line 524indicates to interface control 520 that the switch is deactivated.Interface control 520 may place data and control signals in a highimpedance state in response to the deactivation of switch 522. This mayreduce noise on data and control lines when the connection betweenconnector 512 and connector 518 is broken.

[0023] The magnet or magnets employed with the present invention may bedisposed on an outer surface of a module or docking unit, in thebulkhead of a module or docking unit, or may be disposed interior to thedocking unit or module. FIG. 6 depicts magnet placement. Unit 600 may bea docking unit or module comprising bulkhead 602. A magnet may be placedexternal to the unit as shown for magnet 604. A magnet may be placed inan opening in bulkhead 602 as shown by magnet 606. Magnet 606 may bedisposed in a carrier made of a non-magnetic material, such as aluminum,for example, limiting electromagnetic emissions. A magnet may bedisposed in a cavity in bulkhead 602 as shown by magnet 608. Magnet 608may be flush with the outer surface of bulkhead 602. A magnet may beplaced on the interior of unit 600 as shown by magnet 610. When magnet610 is placed on the interior of bulkhead 602, a portion of bulkhead 602is comprised of a non-magnetic material, such as aluminum, for example.Further, the area of bulkhead 602 in which a magnet is positioned may beof different thickness than other areas of bulkhead 602. The presentinvention may employ some or all of the magnet placements depicted inFIG. 6 and may employ a carrier of non-magnetic material. Althoughprevious figures depict interior positioning of magnets, the teaching ofFIG. 6 may be applied to these figures such that magnets may be placedinterior, in or through a bulkhead, or exterior to a docking unit ormodule.

[0024] The present invention may be employed with module to docking unitconnections, docking unit to docking unit connections, ormodule-to-module connections wherein modules may connect with othermodules and may be cascaded or otherwise interconnected. The termbulkhead may be employed to refer to a surface of a docking unit ormodule. The present invention provides a new system and method forinterfacing electrical and electronic components that limits exposure tounsafe voltages, reduces electromagnetic radiation by reducing thenumber of openings needed in a docking unit or module, and by placingdata and control signals in a high impedance state when a module is notpresent. The present invention also reduces the number of pins requiredin connectors by employing the magnetic proximity controller interfaceto signal that a module is present rather than employing a signal pin inthe connector. This results in less costly connectors and eliminates apossible point of failure. The present invention may also be employed tocontrol an interface when a module is removed. A magnetic proximitysensor in a module may be employed to sense removal prior to anelectrical connection at a connector being broken, allowing the moduleto place signals in a state such that spikes do not occur or are reducedwhen the connection is broken. Advantageously, the present inventionprovides a system and method for interfacing module components thatoffers safety, reduced electromagnetic radiation and reduced stress tocircuitry.

[0025] The foregoing description of the invention has been presented forpurposes of illustration and description. It is not intended to beexhaustive or to limit the invention to the precise form disclosed, andother modifications and variations may be possible in light of the aboveteachings. The embodiment was chosen and described in order to bestexplain the principles of the invention and its practical application tothereby enable others skilled in the art to best utilize the inventionin various embodiments and various modifications as are suited to theparticular use contemplated. It is intended that the appended claims beconstrued to include other alternative embodiments of the inventionexcept insofar as limited by the prior art.

I claim:
 1. A method for removably connecting a power supply module to adocking unit in an electrical system comprising: producing a signal froma switch disposed in said docking unit when said power supply module isdocked to said docking unit wherein said switch is responsive to amagnetic field produced by a magnet affixed to said power supply module;inputting said signal to a power control circuit; transferring a firstvoltage from said power control circuit to said power supply module whensaid signal is active; inhibiting transfer of said first voltage fromsaid power control circuit to said power supply module when said signalis not active; and transferring a second voltage from said power supplymodule to said docking unit.
 2. The method of claim 1 furthercomprising: generating a module presence indicator signal employing saidsignal.
 3. The method of claim 1 wherein said step of transferring saidfirst voltage from said power control unit to said power supply modulewhen said signal is active further comprises: ramping said firstvoltage.
 4. The method of claim 1 wherein said switch is a reed switch.5. A method for removably connecting a storage system module to adocking unit in an electrical system comprising: producing a signal froma switch disposed in said docking unit when said storage system moduleis docked to said docking unit wherein said switch is responsive to amagnetic field produced by a magnet affixed to said storage systemmodule; inputting said signal to a power control circuit; transferring afirst voltage from said power control circuit to said storage systemmodule when said signal is active; inhibiting transfer of said firstvoltage from said power control circuit to said storage system modulewhen said signal is not active; enabling data signals connecting saidstorage system module and said docking unit when said signal is active;and placing said data signals in a high impedance state when said signalis not active.
 6. The method of claim 5 further comprising: generating amodule presence indicator signal employing said signal.
 7. The method ofclaim 5 wherein said step of transferring a first voltage from saidpower control unit to said storage system module further comprises:ramping said first voltage.
 8. The method of claim 5 wherein said switchis a reed switch.
 9. The method of claim 5 wherein said storage systemmodule is a disk drive module.
 10. The method of claim 5 wherein saidstorage system module is a storage controller module.
 11. A method forremovably connecting an storage system module to a docking unit in anelectrical system comprising: producing a first signal from a firstswitch disposed in said docking unit when said storage system module isdocked to said docking unit wherein said first switch is responsive to amagnetic field produced by a first magnet affixed to said storage systemmodule; producing a second signal from a second switch disposed in saidstorage system module unit when said storage system module is docked tosaid docking unit wherein said second switch is responsive to a magneticfield produced by a second magnet affixed to said docking unit;inputting said first signal to a power control circuit; transferring afirst voltage from said power control circuit to said storage systemmodule when said first signal is active; inhibiting transfer of saidfirst voltage from said power control circuit to said storage systemmodule when said first signal is not active; driving data signals fromsaid docking unit to said storage system module when said first signalis active; placing data signals output by said docking unit in a highimpedance state when said first signal is not active; driving datasignals from said storage system module to said docking unit when saidsecond signal is active; and placing data signals output by said storagesystem module in a high impedance state when said second signal is notactive.
 12. The method of claim 11 further comprising: generating amodule presence indicator signal employing said first signal.
 13. Themethod of claim 11 wherein said step of transferring a first voltagefrom said power control circuit to said storage system module when saidfirst signal is active further comprises: ramping said first voltage.14. The method of claim 11 wherein said switch is a reed switch.
 15. Themethod of claim 11 wherein said storage system module is a disk drivemodule.
 16. An electrical connection system comprising: a cabinetincluding at least one docking unit; a module that may be docked to saiddocking unit; a non-magnetic area in a portion of at least one surfaceof said docking unit; a magnet affixed to said module; a switch disposedin said non-magnetic area of said docking unit; and a circuit thatreceives a switch signal from said switch and that transfers a voltagefrom said docking unit to said module through a connector when saidswitch signal is active and that inhibits transfer of said voltage fromsaid docking unit to said module when said switch signal is not active.17. The system of claim 16 further comprising: an indicator signalderived from said switch signal that indicates the presence of saidmodule
 18. The system of claim 16 wherein said circuit ramps saidvoltage supplied to said module.
 19. The system of claim 16 wherein saidmodule supplies a second voltage to said docking unit.
 20. The system ofclaim 16 wherein said module is a storage controller module.
 21. Thesystem of claim 16 wherein said module is a disk drive module.
 22. Thesystem of claim 16 wherein said circuit enables said docking unit todrive data signals to said module.
 23. An electrical connection systemcomprising: a cabinet including at least one docking unit; a module thatmay be docked to said docking unit; a first non-magnetic area in aportion of at least one surface of said docking unit; a first magnetaffixed to said module; a first switch positioned in said firstnon-magnetic area of said docking unit; a first circuit that receives afirst switch signal from said first switch and transfers a voltage fromsaid docking unit to said module through a connector when said firstswitch signal is active and that inhibits transfer of said voltage fromsaid docking unit to said module when said first switch signal is notactive. a second non-magnetic area in a portion of at least one surfaceof said module; a second magnet affixed to said docking unit; a secondswitch positioned in said second non-magnetic area of said module; and asecond circuit that receives a second switch signal from said secondswitch and that enables said module to drive data signals to saiddocking unit when said second switch signal is active.
 24. The system ofclaim 23 further comprising: an indicator signal derived from said firstswitch signal that indicates the presence of said module
 25. The systemof claim 23 wherein said first circuit ramps said voltage supplied tosaid module.
 26. The system of claim 23 wherein said module supplies asecond voltage to said docking unit.
 27. The system of claim 23 whereinsaid module is a storage controller module.
 28. The system of claim 23wherein said module is a disk drive module.
 29. The system of claim 23wherein said first circuit enables said docking unit to drive datasignals to said module.